Golf swing training apparatus

ABSTRACT

The time and position of a golf club head are sensed photoelectrically at selected stations along a practice swing, and corresponding characteristics of the swing and of the resulting ball flight are computed electronically and displayed to the player. The lateral club position is sensed accurately at spaced stations near the ball for computation of the swing direction. The clubhead attitude at impact is determined by two sensors spaced along the club face. Matrix circuitry computes the nature of ball flight from the club attitude and swing direction. Ball distance is computed by generating a pulse rate that varies with the ball flight characteristic, and counting the pulses during the portion of the swing between set points. The electronic computing system is reset during a backswing, and all computations are completed during the forward swing. The display is activated automatically as the swing is completed, and remains on until the ball is addressed for a new swing.

United States Patent [72] Inventor Kenneth K. Wright 800 Rlrn Road,Pasadena, Calif. 91107 (21] Appl. No. 865,665 [22] Filed Oct. 13,1969[45] Patented Aug. 24, 1971 {54] GOLF SWING TRAINING APPARATUS 17Claims, 8 Drawing P1.

[52] U.S.C1. 273/l86 R, 273/185, 73/379 [51) Int. CL A631) 69/36 [50]Field 01 Search 273/183, 184, 185, 186; 73/379 [56] References CitedUNITED STATES PATENTS 2,399,668 5/1946 Francis 273/186 R 2,571,97410/1951 Wa1ker...... 273/186 R 2,825,569 3/1958 Alvarez 273/186 R3,020,049 2/1962 McNeill 273/186 R 3,117,451 1/1964 Verne Ray et a1.73/379 Primary Examiner-George J. Marlo Attorney-Charlton M. LewisABSTRACT: The time and position of a golf club head are sensedphotoelectrically at selected stations along a practice swing, andcorresponding characteristics of the swing and of the resulting ballflight are computed electronically and displayed to the player. Thelateral club position is sensed accurately at spaced stations near theball for computation of the swing direction. The clubhead attitude atimpact is deter mined by two sensors spaced along the club face. Matrixcircuitry computes the nature of ball flight from the club attitude andswing direction. Ball distance is computed by generating a pulse ratethat varies with the ball flight characteristic, and counting the pulsesduring the portion of the swing between set points. The electroniccomputing system is reset during a backswing, and all computations arecompleted during the forward swing. The display is activatedautomatically as the swing is completed, and remains on until the ballis addressed for a new swing.

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PATENIEU AuB24 IHYI mean 3 nr 3 a z @w f e P. g fi vIH h w J A 2 m: r wx a. m E a a $1 K P z T r T 6 H 0 7% 0M 0 if 4 m k 5 2 3 M M M e e 2 TVPW f l|| WM fl fwmmw f a Q a p. Q 2 a GOLF SWING TRAINING APPARATUS Thisinvention concerns practice golf devices for detecting and indicatingautomatically the quality of individual golf swings.

FIELD OF THE INVENTION More particularly, the invention provideselectronic means for measuring certain selected characteristics of agolf swing, for deriving from the resulting electrical signalsinformation as to the ball flight that would normally result, forcomputing one or more overall evaluations of the swing, and fordisplaying the resulting data to the player.

The invention utilizes a captive or simulated ball, and obtains allnecessary information by sensing the movement of the club head. Movementof the club head during a practice swing is measured by distinct groupsof sensors, typically comprising photosensors which respond to theshadow of the club head formed by a single light source. Although thesensors of each group are suitably arranged to measure a particularfeature of the swing or to perform a specific function, the output fromeach group is typically employed in the computation of more than onebasis for swing evaluation.

Since no actual ball flight is required, the device may be extremelycompact and may be made conveniently portable. In preferred form of thedevice, all operations are performed electronically. The substantial orcomplete absence of moving parts makes the machine economical to buildand reliable in operation. Moreover, the device of the invention doesnot require a special club, but can be operated typically with anywooden driver, so that each player can use his own club.

THE PRIOR ART The practice device of the invention typically performssome of its functions in a conventional manner. Other features, however,are completely new, or utilize new principles of operation. Inparticular, US. Pat. No. 2,571,974 to John Walker employs light beamsand photosensors for measuring club movement, but with only a one-to-onedisplay of the light beams that are intercepted. Walker also includes asingle sensor for supplying plate voltage to some of his vacuum tubes inresponse to the back swing of the club, thereby arming" the system.However, his mechanical relays are reset to idle condition after eachswing by individual timing capacitors.

US. Pat. No. 3,020,049 to Alvin L. McNeill also uses photosensors andprovides circuitry for computing the direction of swing. However, thephotocells in each of his two rows l8 and 20 must be spaced apart widelyenough so the club shadow will affect only one cell of each row. Thatrequirement limits the accuracy with which the swing direction can bemeasured and prevents any effective measurement of swing direction closeto the ball position.

SUMM ARY OF THE INVENTION The present system has the advantage ofcontinuing to display the score for each swing until the display isautomatically turned off as the player addresses the ball for the nextswing. The display then remains off during normal small club movementsor waggles and is turned on again only in response to the followthroughportion of the next swing. For each swing, the computing portion of thesystem is reset to zero condition in response to the backswing, and thenew swing computation is carried out electronically during the course ofthe forward swing, and is ready when the display is turned on.

A further feature of the present invention permits accurate measurementof the swing direction essentially at the point of impact. That isaccomplished by providing two spaced rows of sensors extendingtransversely of the swing direction, and deriving from the sensoroutputs two signals that represent the positions at which the remoteedge of the club shadow crosses the respective rows. With that techniqueof computation, the sensors of each row can be placed as close togetheras required to produce the desired accuracy.

The invention includes sensing mechanism for detecting the attitude ofthe club head essentially at the instant it strikes the ball, permittingevaluation of the swing in terms of square, open or closed attitude, forexample.

The invention further utilizes the measurement of club attitude incombination with the measurement of swing direction for deriving anassessment of the flight characteristics of the ball. All threevariables are preferably indicated to the player. Thus, the player isseparately informed of the swing direction, the club attitude and theflight characteristic derived from them.

The invention further utilizes a distinctive method for com puting aprobable distance of flight of the ball. The rate of swing of the clubbetween predetermined points is timed by a clock that operates atvariable pulse rate. The clock rate is automatically selected inaccordance with the computed flight characteristic computed for thatsame swing. The clock rates are so selected that the resulting digitaloutput is an appropriate measure of the distance in yards.

DESCRIPTION OF DRAWINGS A full understanding of the invention, and ofits further objects and advantages, will be had from the followingdescription of an illustrative system for carrying it out. Thatdescription is to be read in conjunction with the accompanying drawings,in which FIG. I is a somewhat schematic perspective representing anillustrative golf practice system in accordance with the invention;

FIG. 2 is a block diagram illustrating the system;

FIG. 3 is a schematic diagram representing typical circuitry forderiving swing and flight data;

FIG. 3A is a schematic diagram showing a portion of FIG. 3 in furtherdetail;

FIG. 4 is a schematic fragmentary plan at enlarged scale. illustratingthe measurement of different swing angles;

FIG. 5 is a schematic plan illustrating different swings having the sameswing angle;

FIG. 6 is a schematic diagram representing typical circuitry forderiving club attitude data and for control of the display; and

FIG. 7 is a schematic diagram representing typical circuitry for thedistance computation.

ILLUSTRATIVE EMBODIMENT OF THE INVENTION Referring first especially toFIG I, the present illustrative practice device is mounted on a flatbase 10. The forward portion of base I0 provides the playing surface I9,which may be covered with artificial grass. A supplementary platform orground surface is provided adjoining base edge II for the player tostand on. However, such a surface may be constructed integrally withbase I0 if preferred.

Base 10 carries suitable indication of an aiming point or impact pointfor the golf swing, preferably in the form of a cap' tive or dummy ball,which may be of any conventional construction. As illustrated, the ball12 is mounted on the flexible resilient arm 13, carried by the post 14.After each swing the ball is resiliently returned to its normalposition, as shown in the drawing. Base 10 also carries an indication ofthe direction in which the ball is to be driven, thus defining thecorrect direction of swing. That direction may be shown only indirectly,as by the front edge 11 of base II], or by the ball or its support; or aline or arrow may be represented on the base surface, as indicated atIS.

The main instrument frame also includes the column 16, rigidly mountedon base 10 behind the ball as seen by the player. Column 16 is spacedfar enough from the ball to be out of the way of the swing, but itsupper end preferably projects toward the player, typically at aboutwaist level. Column I6 carries the display panel 17, on which aredisplayed the various scores for each individual swing. Panel 17 formsthe front face of a housing 20 for the computing circuitry and displaylights.

Movement of the club head is detected by a plurality of photosensorswhich detect interruption of respective light beams that extend betweenselected points of base and of column I6. In the preferred structureshown in FIG. 1, the photosensors are mounted below the surface of base10 and are all illuminated by the single light source 18, which ismounted on column 16 close to the axis about which the club headnormally swings. The sensors are protected by windows, not explicitlyshown, which may be formed as lenses for concentrating the lightreceived from source 18.

It will be evident that separate light sources may be provided on column16 for each group of sensors, or for each individual sensor, andsuitable lenses at the source or sources may concentrate the light intorelatively intense beams. Also, the light may be projected in theopposite direction, from individual sources mounted in base 10 torespective sensors on column 16. However, in the present description thelower ends of the light beams will be referred to for convenience as thesensors. Although the light paths may be made approximately or exactlyvertical, it is generally preferred to group the upper ends of the lightpaths close together, and to take account of their different angles ofinclination in the detailed placement of their lower ends and in thedetailed design of the computing circuitry to be described.

The sensors 20 are arranged in several functional groups, typicallyincluding the reset sensors 21, the swing direction sensors comprisingthe two sensor rows 22 and 23, the club face attitude sensors 24, andthe display enabling and range sensors 25.

Reset sensors 2i and display sensors are arranged in respective rowsextending transversely of the swing direction near the right and leftedges of base 10, as seen by the player. The sensors of each row arespaced apart slightly less than the width of the shadow ofa typical clubhead, and each row contains enough sensors, shown illustratively asthree, to insure that the club shadow will pass over at least one sensorof each row. At least sensors 25 are spaced far enough from the ball 12to be clear of the club shadow during the preliminary movements of theclub that a player usually performs prior to an actual swing.

The two groups of swing direction sensors 22 and 23 comprise rowsextending transversely of swing direction 15, initial row 22 beingspaced appreciably ahead of ball 12 and final row 23 being closelyadjacent the ball. The sensors of each row are arranged quite closetogether, typically of the order of half an inch or less, so that theclub head shadow normally may cover several sensors of each row. Therows are so placed that during a normal swing about half of the sensorsof each row are shaded momentarily by the club, the remaining sensorslying outside the shadow beyond the toe of the club.

Sensor group 24 comprises only two sensors, mutually spaced on a lineclose to the ball position and parallel to the leading edge of the clubhead shadow during a proper swing, so that the shadow then reaches bothsensors simultaneously. However, if the club face is not strictlyperpendicular to the ball in a horizontal plane, one sensor is shadedslightly ahead of the other. Sensors of groups 22, 23 and 24 are shownat en larged scale in FIG. 4.

The functions of the several sensor groups will now be described, withspecial reference to the block diagram of FIG. 2. Electrical connectionsin that and other drawings are usually shown as single lines, but maycomprise multiple wires.

Reset sensors 21 are connected in "or configuration, as indicated at 30,and are therefore all functionally equivalent. Momentary shading of anyone of the sensors 21 produces in circuitry 31 one or more electricalreset pulses that are delivered to several points of the system vialines indicated only schematically in FIG. 2 at 32. The reset pulse orpulses release all memory devices within the system and return thevarious computing circuits to normal or zero condition. The system isthereby cleared of the previous swing and of the effects of any wagglesthat have been made, and is ready to receive new input signals from theforward swing.

Display and range sensors 25 are connected in or" configuration, asindicated at 34. The output on the line 35 from OR gate 34, in responseto momentary shading of any one of the display sensors, operates thedisplay control and memory circuit 36. One output from control circuit36 on the line 37 energizes the display portion of the system, indicatedgenerally at 60, for receiving and displaying on panel 17 (FIG. 1) a newset of output signals from the computing circuits. Since allcomputations are carried out electronically, final results are availablewhen the club head reaches display enabling sensors 25. A second outputsignal is generated by display control circuitry 36 on the line 38. andis utilized to disable action by any sensors of groups 23 and 24 thatmight be shaded momentarily by the ball I2 during its oscillations aboutsupport 14 after each swing. The negate signal may also be supplied ifdesired to sensors of groups 21 and 22 to prevent disturbance of thedisplay by accidental shading of such sensors by the club head orotherwise.

However, the negate signal is withheld from at least one sensor that isclear of the ball shadow and is in position to be shaded by the clubhead while addressing the ball. That sensor may be specially provided,but will be assumed for illustration to be the nearest sensor of thegroup 24. That sensor detects the club head when the player addressesthe ball in preparation for the next practice swing and delivers areadiness signal via the line 39 to display control 36. That readinesssignal resets the memory of control 36, deleting the output signals onlines 37 and 38. The display is thereby turned off and the disabledsensors are restored to normal condition. The display then remains darkduring preparation for the swing and during most of the swing itself.Practice waggles will be detected by the sensors, but the resultingspurious computations are not displayed and cause no problem since theyare eliminated by the reset signal which is developed by sensors 2]first in response to the backswing and again during the downswingv Theoutputs from each of the swing direction sensors in rows 22 and 23 arefirst stored in memory devices, indicated schematically at 40 and 42 ofFIG. 2. The signals are then supplied to discriminating circuits 4i and43, which develop for each row of sensors a signal that represents indigital form the position of the remote edge of the club head shadow asit crosses that row. That signal for each row may be arranged torepresent the last sensor that lies within the club shadow, or the firstsensor that escapes the shadow. The detailed correspondence isimmaterial so long as the signals for the initial and final rows 22 and23 are suitably correlated. That processing technique permits effectivedetermination of the club position to substantially any desiredaccuracy, limited only by the closeness of spacing of the sensors ofeach row.

The position signals for sensor groups 22 and 23 are used to develop asignal representing the angular deviation of the ac tual club path fromthe normal or correct" direction, regardless of its transverse position.That angular deviation signal is derived effectively instantaneously bymatrix circuitry indicated at 46 in FIG. 2, and is supplied via the line47 to the swing direction readout portion 64 of display 60. The swingdirection is typically displayed in the form of an appropriatedesignation such as straight, push, pull, hard push or hard pull.

The position signal for sensor group 23 also represents the transverseclub position essentially at the moment of impact, and is therefore ameasure of the horizontal point on the club face at which impact takesplace. That signal is delivered from discriminating circuit 43 via theline 44 to circuitry for displaying the club face contact point,indicated at 62. That display typically comprises a portrayal ofa clubface with an illu minated spot at the appropriate contact point.

The signals from the two club face attitude sensors 24 are supplied tologic circuitry 48, which may be designed to deter mine the club faceangle at the moment of impact with any desired degree of precision anddetail. In the present illustrative system, logic circuitry 48 has threeprimary alternative outputs, supplied as control signals via the line 52to the flight matrix 50. One of those signals indicates substantiallycorrect attitude of the club face, and the others show, if the club isnot square, in which direction it is tilted. An auxiliary signal isresponsive to the degree of that tilt, typically indicating whether itexceeds a selected threshold angle. All four output signals are suppliedvia the line 49 to the attitude readout device 61, where they typicallyappear as the appropriate one of the designations square, open, closed,wide open and wide closed.

The system also obtains information as to the velocity of the club headas it strikes the ball, presenting that information in terms of thedistance the swing is likely to produce. The distance computation isperformed by timing circuitry 54, which counts clock pulses during aperiod that is initiated by a signal on the line 56 from one of sensors24 and is terminated by a signal on the line 57 from sensors 25. Thenumber of counts is therefore inversely related to the speed of the clubhead. In addition, the clock rate is regulated under control of anoutput signal from the flight matrix 50 (see below), supplied via theline 53. That regulation takes appropriate account of the computedcharacter of the swing. The resulting distance signal on the line 58 istherefore a realistic representation of the yards carried by the shot,and is supplied to the yards readout device 63 as a further criterion ofswing quality.

In addition to the specific items of swing information outlined above,each of which constitutes a valid basis for swing evaluation and istherefore an item of interest to the player, the present inventioncomputes from those items one or more general criteria for evaluation ofthe swing. Such criteria are typically indicated in terms of anappropriate brief description of the probable result of the measuredswing, which description is displayed to the player in addition to thedetailed components from which it was derived. Such display may besupplemented, if desired, by more elaborate indications, such aspictorial characterizations of the probable distance traveled by theball.

For illustrative derivation of overall criteria, the output signals fromswing matrix circuitry 46 and from club face attitude logic circuitry 48are supplied via the respective lines 51 and 52 to computing circuitryof matrix form, designated in FIG. 2 as flight matrix 50. That matrixcircuitry is designed in accordance with definite assumptions, based ongolfing experience and the laws of physics, as to the type of ballflight that is produced by a golf swing having the club face attitudeand the type of swing direction represented by the specified inputsignals. Like the input signals from which it is derived, the outputfrom the flight matrix circuits can be designed to represent any desireddegree of detail. The resulting flight signal is supplied via the line53 to flight readout device 65, where it typically appears as anappropriate word or phrase, selected from an available assortment suchas perfect, face, draw, push, pull, hook, slice, hard hook, hard slice,and bobble.

FIGS. 3 and 3A represent typical circuitry for instrumenting swingmatrix 46 and flight matrix 50, together with circuits for developinginput signals to the former. Throughout these and other circuit drawingsthe signal designations on various lines represent the signal that arepresent in normal or reset condition of the system, immediately prior toa forward swing. Those signals are always either a definitely positivepotential, designated or "plus or a relatively negative potential,typically ground, designated or minus.

Initial row 22 of the swing direction sensors is shown illustratively ascontaining only two individual sensors, represented in FIG. 3 togetherwith their preamplifier circuits at 221 and 22-2; and final sensor row23 is shown with four sensors which are similarly indicated at 23-!through 23-4. As shown in FIG. 3A for a typical sensor, each of thosecircuit comprises a solid-state photovoltaic cell Pc connected with theindicated polarity in the base circuit of an amplifying NPN transistor()1. The collector resistor R1 receives positive power via negate line38 from a switchable control which is typically incorporated in displaycontrol 36, to be described (FIG. 6,), and which deletes power from thetransistor during operation of the display. Accordingly, once a swinghas been completed and the swing characteristics have been displayed,the display cannot be interfered with by further signals from photocellFe.

The light from source 18 (FIG. I) normally maintains Fe in voltagegenerating or "011 condition, making 01 conductive. The transistorcollector is thereby essentially grounded, producing the indicatednormal negative signal on the output line 80. When covered by theclubhead shadow the photocell turns ofi', cutting off the transistor andsupplying a positive signal from negate line 38 to line via thecollector re sistance R1.

The particular logic or computing circuits to be described are selectedsomewhat arbitrarily from the very wide variety of available circuittechniques. An important criterion in the present illustrative designhas been the convenient availability of integrated circuits comprisingpairs of NPN transistors and load resistors connected to form NAND-NORgates of conventional type. Each of those gates has two inputs and asingle output. If either input is plus the gate output is minus. Only ifboth inputs are minus is the output plus. Such a gate circuit performsthe NOR function when operating in positive logic, that is, when theplus voltage is considered the significant signal. When the minusvoltage is considered the significant signal, as in some portions of thecircuit of FIG. 3, the gate performs the NAND function. Such NAND-NORgates are conveniently usable as simple inverting circuits, and may becombined to form flip-flops and other logic blocks. Such combinationsare not always theoretically the simplest circuits for the presentpurpose, but have proved in practice to be highly convenient, economicaland effective.

Memory circuits 40 and 42 of FIG. 3 comprise a bistable flip-flop FF foreach sensor, each FF comprising two NOR gates A and B. Each memory FFnormally produces a negative output signal on the line 82. That signalis changed to plus in response to a momentary plus signal on input line80, and the output then remains plus until reset to negative by apositive reset pulse supplied via reset line 32.

Typical circuitry for each memory FF is shown in FIG. 3A. NOR gate Acomprises the two NPN transistors 02 and 03, with their emittersgrounded and their collectors connected together and via the resistanceR2 to 3+. The two input signals for the gate are supplied to therespective transistor bases, and the gate output is taken from thecollector junction. NOR gate B comprises the transistors Q4 and Q5,connected like gate A with collector resistance R3. The input signals togate A with are taken from line 80 and via the line 84 from the outputof gate B, respectively. The respective inputs to gate B are from theoutput line 83 of gate A and from reset line 32. The output from gate Bis supplied as the FF output to line 82. In each gate, ifeither inputsignal is plus its transistor conducts and the gate output is negative.Only if both inputs are negative is the output plus.

In operation of the present illustrative memory circuit, a positivereset pulse on line 32 turns on Q5, resetting the FF output on line 82to negative. That negative signal is coupled to Q3, cutting it off.Since O2 is also cut off by the normally negative input on line 80 thenormal output of gate A is positive. That plus signal is coupled to O4,rendering it conductive and thereby maintaining the negative outputsignal from gate 8 after decay of the reset pulse cuts off 05.Thereafter, a momentary plus signal from line 80 turns on Q2, shiftingthe output of gate A to negative. Since both inputs to gate B are thennegative, the output on line 82 is shifted to plus. That signal turns onQ3, holding the FF in active state after decay of the original signal online 80.

Discriminating circuits 41 and 43 as already indicated, perform theprimary function of producing a signal which represents the points ofthe respective sensor rows 22 and 23 that were crossed by the edge ofthe clubhead shadow furthest from the player. The circuits showncomprise one NOR gate D and two inverting circuits C and E for each ofthe sensors of the row. The inverters E serve primarily to provideoutput signals of suitable polarity for the particular form of swingmatrix circuitry 46, to be described, and might be omitted withdifferent system design. Each of the NOR gates is typically identical inconfiguration and manner of operation to NOR gate A or B of FIG. 3A.

For each sensor row 22 and 23, the memory output signal on line 82 foreach sensor except the one farthest from the player is inverted at C andis then supplied as a normally plus input to NOR circuit D. The otherinput to D is taken via the line 92 directly from the memory output forthe sensor next farthest from the player. The output from NOR circuit Dis negative unless both inputs are negative, that is, unless theassociated sensor was shaded by the clubhead swing and the sensor nextfarther from the player was not shaded. Under that condition the outputis plus. After inversion at E, the final discriminator output signal toswing matrix 46 is negative only for the most remote sensor within theclubhead shadow. For other sensors within the shadow the final outputcontinues positive; although the NOR gate receives a negative input fromC, the input on line 91 is plus. And the final output for all sensorsbeyond the shadow naturally retains its normal value.

The discriminating circuitry for the sensor of each row farthest fromthe player is simply a direct connection from input line 82 to inverterE, since whenever that sensor is shaded it is assumed to be at the edgeof the shadow. Similarly, if no sensor of a row is shaded, the shadowedge is assumed to be just inside the sensor nearest the player. Anoutput signal corresponding to that condition is produced on theauxiliary output line 90-0 for sensor row 22 and on the line 91-0 forrow 23. Those signals are developed by a NOR gate D which receives oneinput via line 92 from the first sensor of the row and the other inputfrom a continuous source of negative signai, shown as a simple groundwith current limiting series resistance R5. Since that NOR circuit Dnormally receives two negative inputs. its output is normally positive,but is inverted at E to negative, as indicated. If the first sensor ofthe row is shaded that final output shifts to positive.

Accordingly, the final output from each of the discriminating circuits41 and 43 to swing matrix 46 comprises a negative signal on theparticular line 90 or 91 that corresponds to the most remote sensorwithin the clubhead shadow, all other lines 90 and 91 carrying a plussignal. Since the significant signals are minus, the immediatelyfollowing portion of the circuitry conforms to negative logic.

In addition to the output signal supplied from discriminator 43 to swingmatrix 46, the same output signal may be utilized as an indication ofthe point on the clubface at which the ball was contacted. The signalsfor supply to club face readout device 62 (FIG. 2) are typically tappedfrom discriminator 43 just in advance of inverters E, as indicated bythe output lines 44-0 through 44-4. Those lines then provide a positivesignificant signal for driving the display.

Before discussing swing matrix 46, it will be useful to consider FIG. 4,which indicates a club head 100 in a typical position about to strikeball 12, and with its remote edge 102 moving along the path 96. Fiveillustrative paths 94 through 98 correspond to respective swing anglesthat are denoted hard pull, pull, straight, push and hard push. Allthose lines pass between sensors 21-1 and 21-2 and therefore produce asignal from discriminator 41 on line 90-1. The corresponding signalsfrom discriminator 43 are on the respective lines 91-0 through 91-4, asindicated in the figure. Each of the swing paths shown in FIG. 4 mightbe displaced laterally in either direction, leading to a different setof signals, but still representing the same swing angle. In the presentsystem there are. in general. three different sets of discriminatorsignals which correspond to each swing angle, as represented in FIG. 5at 97a, 97b and 97c for the typical case ofpush. Although only two suchsets exist that uniquely represent hard pull and hard push, it isconvenient to group with them the signal sets 90-2, 91-0 and 90-0, 91-4,corresponding to the still more extreme angular deviations in therespective directions.

Swing matrix 46, as shown in FIG. 3, comprises a plurality of gates F,each of which is typically identical in structure to NOR gate A or B ofFIG. 3A, but which perform the function of NAND gates in view of thenegative logic in which they operate. Each of those NAND gates receivesone of its inputs from discriminator 41 and the other from discriminator43, the wiring being such that each gate corresponds to a unique pair ofdiscriminator signals. Each such signal pair corresponds to a definiteswing direction, three signal pairs corresponding to each of thedesignated swing directions. The three NAND gates for each of thoseswing directions are grouped together in FIG. 3, and their outputs aresupplied as inputs to a common gate G, which may be like NOR gate A or Bof FIG. 3A but with three parallel transistors instead of two. The gatesG operate in positive logic and function as NOR gates. They haverespective outputs on the lines 51-1 through 51-5, all those outputsbeing plus except that the signal corresponding to the direction of theactual swing is minus. In normal or reset condition of the system asillustrated, the sig nificant minus output signal from matrix 46 isalways on line 51-2. That is a coincidence, and results from the factthat discriminators 41 and 43 produce reset signals on lines -0 and91-0, and that those signals happen to correspond to pull due to thegeometry ofthe present sensors.

Flight matrix 50 of FIG. 3 will be described below, after consideringclubface attitude logic 48.

FIG. 6 represents schematically illustrative circuitry for clubfaceattitude logic 48, which operates under control of the two photosensors24-1 and 24-2. Those sensors are shaded simultaneously by the leadingedge 104 ofclub head if the club attitude is correct (FIG. 4). If theclub reaches the point of impact in open position sensor 24-1 is shadedfirst, if in closed" position 24-2 is shaded first. Those alternativeconditions are discriminated by logic circuitry 48, producing a positiveoutput signal to display 60 on the appropriate one of the three outputlines 49-1, 49-2 and 49-3, and a negative output signal to flight matrix50 on the corresponding output line 52-1, 52-2 or 52-3.

Each sensor is typically a photovoltaic cell connected in suitablepreamplifying circuitry, which may be similar to that shown in FIG. 3Aor may include additional stages of amplifcation. That circuitryincludes signal inverters, if needed, to produce on the lines 112 ofFIG. 4 respective signals that are negative when the sensors areilluminated and shift momentarily to positive when the clubhead shadowcrosses them.

Those signals are supplied to the timing circuitry 114, comprising thecapacitors Cl and C2 and the resistances R6, R7 and R8, R9 connected asshown. Circuits 114 differentiate the input signals and produce on thelines 113 positive output pulses of controlled duration corresponding tothe leading edge of the clubhead shadow, as well as later negativepulses which correspond to the trailing edge and are not utilized. Thepositive pulses are inverted by the respective inverters J, produc ingnegative signal pulses which are supplied to the NAND gate K. If bothnegative pulses arrive at K close enough in time to overlap, the gateoutput shifts momentarily from negative to positive, applying a positivepulse via the capacitor C3 to the flip-flop circuit FF2, The lattercircuit is typically identical in configuration and operation to FF ofFIG. 3A, and has normally negative output on line 52-1. The incomingpositive pulse shifts that output to positive, indicating square"attitude of the clubhead. The flip-flop acts as a memory circuit to holdthat output until reset by a positive pulse on reset line 32 fromsensors 21 (FIG. 3). The angular tolerance allowed in the club headsquare attitude is readily determined by selection of the componentvalues for timing circuits 114 to produce the desired degree of overlapof the signals reaching NAND gate K.

If desired, the circuitry for producing square signal on line 49-1,including timing circuits 114, flip-flop FF2 and their connectingcircuits, may be duplicated one or more times with different timingrelations in their respective circuits 114. Such a duplicate system isindicated schematically at 120, with output line 49- 4. If the circuits114 of system 120 produce output pulses that are longer than those ofsystem 110, for example, a signal will appear on line 49-4 whenever theclub attitude satisfies a relatively lenient angular tolerance, whilesignals will appear on both lines 49-1 and 40-4 if the more stricttolerance of system 110 is met. The club attitude may thus be indicatedto any desired degree of precision.

To indicate the direction of any deviation from square, the sensorsignals on lines 112 are supplied also via the respective capacitors C5and C6 to the two inputs of the flip-flop FF3. That FF typicallycomprises two NOR circuits of the same type as A and B of FIG. 3A, withtheir inputs and outputs connected as shown in FIG. 6, so that theflip-flop has two input lines and two output lines. FF3 has two stableconditions to which it is set by positive pulses on the respective inputlines, and in which the corresponding output line is negative. In normal condition the circuit may be in either state, being shownillustratively with positive output corresponding to the input fromsensor 24-2. In operation, whichever of the two input pulses arriveslast determines the state of FF3. The output shown therefore representsopen position of the club, in which sensor 24-1 is shaded before 24-2.

The circuit of FIG. 6 also includes means for disabling both open andclosed signals in presence of a square signal on line 49-1. The twooutputs from FF3 are supplied as inputs to the respective NOR circuitsL, which receive their other inputs from the output of FFZ via the line116 and the current limiting resistance R14. NOR gates L can produce apositive output signal only when the input from FF2 is negative, thatis, in absence of a square signal. The presence of NOR gates L alsoinverts the outputs from FF3, so that the significant signal on outputlines 49-2 and 49-3, like that on line 49-1, is the plus signal. Thosesignals are supplied directly to display 60 for controlling clubheadattitude readout 61 (FIG. 2), and are also Supplied, after inversion bythe respective inverters M to flight matrix 50 (FIG. 3).

It is noted that the output on line 112-1 from sensor 24-1 may beamplified, shaped and otherwise modified, as required, to providesuitable control signals on the line 39 for turning the display off, andon line 56 for turning on the counter in distance computer 54 (FIG. 3).Circuitry for that purpose is indicated schematically in FIG. 6 as theamplifier 118. Sensor 24-1 receives power continuously, and is notdisabled during operation of the display. Sensor 24-2, however, mayreceive power via negate line 38, as already described for sensors 22and 23, in order to desensitize the sensor to backlash oscillations ofthe ball 12.

Flight matrix 50, as shown in FIG. 3, comprises the fifteen gates H,which are typically constructed like NOR gates A and B of FIG. 3A, butfunction as NAND gates since they operate in negative logic. Each NANDgate H receives one input from an output line 51 from swing matrix 46and the other input from a line 52 from clubface attitude logic 48 (FIG.6), each gate receiving a unique pair ofinputs. The gate outputs on therespective lines 118-1 through 8-15 are normally minus. The single plusoutput indicates coincidence, for the swing in question, of theparticular swing direction and the particular clubface attitudecorresponding to the one activated gate.

In the present illustrative system, NAND gates H are required to coverall possible signal pairs, and all l5 possible signals might bedisplayed. However, it is generally preferred to reduce the variety ofoutput signals by combining signals that represent generally similarresults with respect to probable flight ofthe ball. Such generallyequivalent signals are supplied to the OR gates I. The final outputsfrom flight matrix 50 then comprise the outputs from those OR gates andalso the outputs from the lines 118 that are considered unique. FIG. 3represents an illustrative selection of such outputs. comprising thelines 53-1 through 53-10. 'lhosc lines 53 are connected to display fillfor driving flight rcadout 65 (FIG. 2). The significant positive signaltypically illuminates on panel 17 (FIG. 1) a suitable flightdesignation, such as those shown in association with the respectivelines in FIG. 3. The same output lines Ill 53 are also connected ascontrol inputs to distance computer 54.

An illustrative form of distance computer 54 is shown in FIG. 7. Acounting circuit, typically of conventional design, is indicatedschematically at 130. Counter is set in operation by a pulse received online 56 from sensor 24-] via amplifier 118 (FIG. 6), and is stopped by apulse received on line 57 from sensors 25 via OR gate 34 (FIG. 2].During its period of operation counter 130 counts positive pulsessupplied via the line 132 from a source to be described. The resultingcount controls an output signal on the line 58 for supply to distancereadout device 63 (FIG. 2). Since the counting period varies inverselywith the club speed, the distance readout is arranged to vary inverselywith the count. In preferred form of the system, counter 130 is arrangedto count down from an initial or reset value which corresponds to anassumed theoretical maximum distance. Each count then reduces theindicated distance by a selected interval. For example, with a binarycounter having a capacity of 16 counts. the reset value may correspondto 400 yards, each pulse reducing that value by 25 yards. The displaydevice then typically has 12 readout values from 25 to 300 yards and ismade unresponsive to counts that would represent unrealistically highdistances.

Pulses are supplied to counter 130 at various alternative rates,depending upon the output signal from flight matrix 50. That signal issupplied via the lines 53 and may control the rate of pulse developmentin any suitable manner. As shown in FIG. 7, the ten alternative signalson lines 53 are reduced to four signals on the lines 134 by combiningsignals that are cssentially equivalent for distance production. That isaccomplished by the NOR gates P, which also invert the significantsignals from plus to minus. Four distinct pulse rates are produced bythe respective oscillators M1 through M4. All oscillators typically runcontinuously, delivering negative pulses at their respective rates f1through f4 to the respective NAND gates 0. One of those pulse trains isselected by the NAND gate that also receives a minus control signal fromits line 134. The selected train is delivered as positive pulses via ORgate R to the line 132 and thence to counter 130. The clock rate thusprovided to the counter is higher the poorer the swing, so that, for anygiven speed of swing, an increasing distance is counted down from theassumed maximum.

The least effective types of swing, represented by a flight signal online 53-], and designated bobble, typically produces essentially zerodistance. With the system as so far described, an appropriate readout isreadily obtained simply be leaving line 53-] open in FIG. 7. Alloscillators M1 through M4 then remain cut off at their NAND gates Q, andcounter 130 remains at its reset value, leaving the distance readoutdark. The connection of line 53-1 shown in FIG. 7 is described below.

The distance-computing system, as so far described, may be modified asdesired, for example to make the indicated distance dependent upon othercharacteristics of the swing, or to vary the relation between the speedof swing and the distance indicated. In particular, one or moreadditional pulse sources may be provided, which supply pulses atselected rates and under controlled conditions to counter 130. As anexample of such modification, FIG. 7 shows a constantly running sourceMo of negative pulses of frequencyfo. Those pulses are supplied as oneinput to a NAND gate S, the other input being a control signal derivedvia the line 138 and the OR gate T from counter 130. When that controlsignal is negative the pulses are delivered by gate S as positive pulscsvia the line 137 to OR gate R, and thence to counter 130 along with theselected train of pulses already described. The control signal on line138 is typically made responsive to counter 130 in such a way that it isnormally minus and shifts to plus after a selected number of counts.Pulses from Mo are thereby supplied to counter 130 only during aninitial counting period. after which they are cut off, decreasing therate at which the indicated distance is reduced. Several such pulsesources may be provided in similar manner, having different rates anddifferent periods of effectiveness.

if the pulse rate of auxiliary source M is sufficiently slow, thecontrol signal from line 138 can be supplied directly to NAND gate S,and line 53l, representing bobble, may be left open as described above.However, it may be desirable to use a pulse rate from Mo that is highenough to produce a distance readout even for a bobble. That isprevented in the system of FIG. 7 by inserting the OR gate T in line 138with its control signal taken from bobble line 53-1. A plus bobblesignal on line 53-1 then makes the control signal at gate S plus,cutting off pulses from Mo regardless of the signal on line 138. Hencein presence of a bobble signal counter [30 receives no input pulses andthe distance display remains dark.

Although selection of the correct pulse rate for a particular swingrequires operation of sensors of groups 22, 23 and 24 and of thecircuits they control, including swing matrix 46, club face attitudelogic 48 and flight matrix 50, the resulting delay in selection of apulse rate is very slight and is found in practice to be only anegligible fraction of the entire counting time, which is essentiallythe time of travel of the club between sensors 24 and 25.

FIG. 6 includes illustrative control circuitry 36 for turning display 60on and off and for developing a negate signal on line 38 to desensitizethe sensors during the display. That cir cuitry comprises the flip-flopFF4, formed of the two NOR gates A and B, typically as shown more fullyin FIG. 3A. One input to FF4 is the line 142, which is normally minusbut can receive a plus pulse via the OR gate U either from reset line 32or via line 39 form sensor 24-1, as in response to a clubhead addressingthe ball. The other input is the line 35, which is normally minus butcan deliver a plus pulse from sensors 25 near the end of the swing. Aninput pulse from line 142 shifts FF4 to the condition shown, with outputline 144 plus. The inverting amplifier 145 then delivers minus voltageto the line 146, idling the relay Ry. An input pulse from line 35 shiftsFF4 to its other state, energizing Ry. The relay switch grounds thecontrol line 37, providing a ground to the entire system of display 60and enabling its various readout devices to be energized by positivesignals on the respective control lines that have been described. Thedisplay remains so energized until FF4 is returned to normal conditionby a reset pulse or by action of sensor 24l, Ground is then lifted,turning the display off.

A second output from FF4 normally supplies positive voltage to negateline 38 but opens that line during the periods that the display is on.That line supplies amplifying power to certain ofthe sensors, typicallythose of groups 22, 23 and 24, but omitting sensor 24-l. As shown,negate line 38 receives its voltage via the inverting amplifier 147 fromthe output of NOR circuit A of FF4. Additional control functions, as forsignal lamps and the like, can be performed via similar connections, orby providing additional switches or switch contacts on relay Ry.

I claim:

1 Golfpractice apparatus, comprising in combination structure defining anormal point of impact of a golf club head during a practice swing and anormal path direction at the point of impact,

two sensors for developing signals in response to passage of the clubhead leading edge essentially at the point of impact, the sensors beingresponsive to laterally spaced points ofthe leading edge,

timediscriminating circuit means receiving the signals and responsive tothe mutual time relation in which the signals are received,

and display means controlled by the circuit means for representingangular relation of the club head leading edge with respect to thenormal path direction.

2. Golf practice apparatus as defined in claim I, and in which said timediscriminating circuit means comprise a flip-flop having two stableconditions to which it is shifted in response to the respective signals,

said display means being responsive to the condition of the ill 3. Golfpractice apparatus as defined in claim 1, and in which saidtime-discriminating circuit means comprise a flip-flop having two stableconditions to which it is shifted in response to the respective signals,

and timing circuit means for producing a coincidence signal in responseto substantial coincidence of said signals,

said display means being responsive to the coincidence signal and beingnormally responsive to the condition of the flip-flop,

and said apparatus including means responsive to the timing circuitmeans for rendering the display means unresponsive to the condition ofthe flip-flop in presence of the coincidence signal.

4. Golf practice apparatus as defined in claim 1, and in which saidtime-discriminating circuit means comprise circuit means responsive tosaid signals for developing respective electrical pulses ofpredetermined duration,

and coincidence circuit means for producing an output signal in responseto coincidence of the pulses,

said display means being responsive to the output signal.

5. Golf practice apparatus as defined in claim 1, and in which said timediscriminating circuit means comprise circuit means responsive to saidsignals for developing a first pair of electrical pulses havingpredetermined duration and having definite time relation to therespective signals,

circuit means responsive to said signals for developing a second pair ofelectrical pulses having predetermined duration longer than the durationof the first pair of pulses and having definite time relation to therespec tive signals,

coincidence circuit means for producing a first output signal inresponse to coincidence of the first pair of pulses and a second signalin response to coincidence of the second pair of pulses,

said display means including means responsive to both the outputsignals.

6. In golf practice apparatus which includes structure defining a normalpath direction and a normal point of impact of a golf club head during apractice swing, mechanism for representing the lateral position of theswinging club head, comprising in combination an ordered series ofsensing devices for developing respective signals in response to passageof a swinging clubhead at respective positions that are progressivelyspaced laterally of the club head path in mutually overlapping relation,

a discriminating circuit for receiving the signals from each pair ofadjacent sensing devices and for producing an output signal only inresponse to combined presence of a signal from the sensing device thatis nearer one end of the series and absence ofa signal from the sensingdevice that is nearer the other end of the series,

and output means for utilizing the output signal from any one of thediscriminating circuits as a representation of the lateral position ofthe club head.

7. Mechanism as defined in claim 6, and including also a discriminatingcircuit for receiving the signal from the sensing device at said otherend of the series, and for supplying to said output means an outputsignal as a representation that the clubhead is beyond said other end ofthe series of sensing devices.

8. Mechanism as defined in claim 6, and including also a discriminatingcircuit responsive to absence of any sensing device signal, forsupplying to said output means an output signal as a representation thatthe club head is beyond said one end of the series of sensing devices.

9. In a golf practice apparatus which includes structure defining anormal path direction and a normal point of impact for a golf club headduring a practice swing, swing direction indicating means comprising incombination two mechanisms as defined in claim 6 for representing thelateral position of the swinging club head, the sensing devices of therespective mechanisms being relatively spaced longitudinally of the clubhead path,

electronic circuit means responsive to the output means of both saidmechanisms and acting to produce a final signal that represents thedirection of movement of the clubhead between the sensing -devices ofthe respective mechanisms,

10. Golf practice apparatus, comprising in combination structuredefining a normal direction and a normal point of impact of a golf clubhead during a practice swing,

first and second sets of signal lines, the signal lines of therespective sets corresponding to selected transverse positions of aswinging club head at first and second longitudinally spaced points ofthe swing,

means for sensing a swinging club head and for producing positionsignals on those signal lines of the respective sets that correspond tothe actual club head positions,

a plurality of output terminals corresponding to respective directionsof club head movement each of which directions corresponds to at leastone pair of said selected transverse clubhead positions,

electronic circuit means including a matrix network of said sets ofsignal lines and responsive to the position signals thereon forenergizing the output terminal that corresponds to the pair of club headpositions represented by the position signals present on the lines,

and display means responsive to the energized terminal ll. Golf practiceapparatus, comprising in combination structure defining a normal pointof impact of a golf club head during a practice swing and a normal pathdirection at the point ofimpact,

first sensing and computing mechanism for sensing a swinging club headand producing a signal representing the angular deviation of a swingingclub head from the normal path direction,

second sensing and computing mechanism for sensing a swinging club headand producing a signal representing the attitude of the club facesubstantially at the point of impact,

electronic circuit means including a matrix network responsive to bothsaid signals for producing a third signal that represents a ball flightcharacteristic corresponding to the sensed swing,

and display means responsive to the third signal.

12. Golf practice apparatus, comprising in combination structurerepresenting a golf ball and defining a normal path ofa golf club headduring a practice swing,

a transducer responsive to a club head when addressing the ball prior tothe swing,

a plurality of transducers normally responsive to a swinging club head,

electronic circuit means controlled by at least some of said transducersfor producing a swing signal that represents a characteristic of theswing,

display mechanism having an active condition in which it is responsiveto the swing signal for displaying said swing characteristic,

first circuit means responsive to the first said transducer fordisabling the display mechanism prior to the swing,

and second circuit means responsive to at least one of said plurality oftransducers for restoring the display mechanism to active condition.

13. Golf practice apparatus as defined in claim 12, and including alsocircuit means for disabling at least some of said plurality oftransducers in response to said second circuit means and for restoringthe disabled transducers to normal condition in response to said firstcircuit means.

14. Golf practice apparatus, comprising in combination structuredefining a normal path of a golf club head during a practice swing,

a plurality of transducers for sensing a swinging club head andincluding transducers acting to produce first and second timing signalsin response to presence of the club head at respective longitudinallyspaced points of the path,

electronic circuit means controlled by at least some of said transducersfor producing a swing signal that represents a characteristic of theswing,

and timing circuit means responsive to the timing signals for producinga distance signal that represents a ball flight distance signal thatvaries inversely with the time interval between the timing signals,

said timing circuit means including means acting under control of theswing signal to modify the distance signal in ac cordance with saidflight characteristic.

15. Golf practice apparatus as defined in claim 14 and in which saidtiming circuit means comprise clock means for producing a series ofclock pulses,

control means for modifying the frequency of the clock pulses undercontrol of the swing signal,

and counting means for counting clock pulses during the time intervalbetween the timing signals.

16. Golf practice apparatus as defined in claim 14, and in which saidtiming circuit means comprise a plurality of oscillating circuits forproducing respective series ofclock pulses at different pulsefrequencies,

gating circuit means responsive to said swing signal for selecting oneof said pulse series,

and counting means for counting the selected series of clock pulsesduring the time interval between the timing signals.

17. Golf practice apparatus as defined in claim 16, and including alsomeans actuable to supply additional pulses at predetermined frequency tothe counting means in addition to said selected pulse series,

and control means for actuating the last said means under control of thecounting means.

1. Golf practice apparatus, comprising in combination structure defininga normal point of impact of a golf club head during a practice swing anda normal path direction at the point of impact, two sensors fordeveloping signals in response to passage of the club head leading edgeessentially at the point of impact, the sensors being responsive tolaterally spaced points of the leading edge, time-discriminating circuitmeans receiving the signals and responsive to the mutual time relationin which the signals are received, and display means controlled by thecircuit means for representing angular relation of the club head leadingedge with respect to the normal path direction.
 2. Golf practiceapparatus as defined in claim 1, and in which said time discriminatingcircuit means comprise a flip-flop having two stable conditions to whichit is shifted in response to the respective signals, said display meansbeing responsive to the condition of the flip-flop.
 3. Golf practiceapparatus as defined in claim 1, and in which said time-discriminatingcircuit means comprise a flip-flop having two stable conditions to whichit is shifted in response to the respective signals, and timing circuitmeans for producing a coincidence signal in response to substantialcoincidence of said signals, said display means being responsive to thecoincidence signal and being normally responsive to the condition of theflip-flop, and said apparatus including means responsive to the timingcircuit means for rendering the display means unresponsive to thecondition of the flip-flop in presence of the coincidence signal. 4.Golf practice apparatus as defined in claim 1, and in which saidtime-discriminating circuit means comprise circuit means responsive tosaid signals for developing respective electrical pulses ofpredetermined duration, and coincidence circuit means for producing anoutput signal in response to coincidence of the pulses, said displaymeans being responsive to the output signal.
 5. Golf practice apparatusas defined in claim 1, and in which said time discriminating circuitmeans comprise circuit means responsive to said signals for developing afirst pair of electrical pulses having predetermined duration and havingdefinite time relation to the respective signals, circuit meansresponsive to said signals for developing a second pair of electricalpulses having predetermined duration longer than the duration of thefirst pair of pulses and having definite time relation to the respectivesignals, coincidence circuit means for producing a first output signalin response to coincidence of the first pair of pulses and a secondsignal in response to coincidence of the second pair of pulses, saiddisplay means including means responsive to both the output signals. 6.In golf practice apparatus which includes structure defining a normalpath direction and a normal point of impact of a golf club head during apractice swing, mechanism for representing the lateral position of theswinging club head, comprising in combination an ordered series ofsensing devices for developing respective signals in response to passageof a swinging clubhead at respective positions that are progressivelyspaced laterally of the club head path in mutually overlapping relation,a discriminating circuit for receiving the signals from each pair ofadjacent sensing devices and for producing an output signal only inresponse to combined presence of a signal from the sensing device thatis nearer one end of the series and absence of a signal from the sensingdevice that is nearer the other end of the series, and output means forutilizing the output signal from any one of the discriminating circuitsas a representation of the lateral position of the club head. 7.Mechanism as defined in claim 6, and including also a discriminatingcircuit for receiving the signal from the sensing device at said otherend of the series, and for supplying to said output means an outputsignal as a representation that the clubhead is beyond said other end ofthe series of sensing devices.
 8. Mechanism as defined in claim 6, andincluding also a discriminating circuit responsive to absence of anysensing device signal, for supplying to said output means an outputsignal as a representation that the club head is beyond said one end ofthe series of sensing devices.
 9. In a golf practice apparatus whichincludes structure defining a normal path direction and a normal pointof impact for a golf club head during a practice swing, swing directionindicating means comprising in combination two mechanisms as defined inclaim 6 for representing the lateral position of the swinging club head,the sensing devices of the respective mechanisms being relatively spacedlongitudinally of the club head path, electronic circuit meansresponsive to the output means of both said mechanisms and acting toproduce a final signal that represents the direction of movement of theclubhead between the sensing devices of the respective mechanisms. 10.Golf practice apparatus, comprising in combination structure defining anormal direction and a normal point of impact of a golf club head duringa practice swing, first and second sets of signal lines, the signallines of the respective sets corresponding to selected transversepositions of a swinging club head at first and second longitudinallyspaced points of the swing, means for sensing a swinging club head andfor producing position signals on those signal lines of the respectivesets that correspond to the actual club head positions, a plurality ofoutput terminals corresponding to respective directions of club headmovement each of which directions corresponds to at least one pair ofsaid selected transverse clubhead positions, electronic circuit meansincluding a matrix network of said sets of signal lines and responsiveto the position signals thereon for energizing the output terminal thatcorresponds to the pair of club head positions represented by theposition signals present on the lines, and display means responsive tothe energized terminal
 11. Golf practice apparatus, comprising incombination structure defining a normal point of impact of a golf clubhead during a practice swing and a normal path direction at the point ofimpact, first sensing and computing mechanism for sensing a swingingclub head and producing a signal representing the angular deviation of aswinging club head from the normal path direction, second sensing andcomputing mechanism for sensing a swinging club head and producing asignal representing the attitude of the club face substantially at thepoint of impact, electronic circuit means including a matrix networkresponsive to both said signals for producing a third signal thatrepresents a ball flight characteristic corresponding to the sensedswing, and display means responsive to the third signal.
 12. Golfpractice apparatus, comprising in combination structure representing agolf ball and defining a normal path of a golf club head during apractice swing, a transducer responsive to a club head when addressingthe ball prior to the swing, a plurality of transducers normallyresponsive to a swinging club head, electronic circuit means controlledby at least some of said transducers for producing a swing signal thatrepresents a characteristic of the swing, display mechanism having anactive condition in which it is responsive to the swing signal fordisplaying said swing characteristic, first circuit means responsive tothe first said transducer for disabling the display mechanism prior tothe swing, and second circuit means responsive to at least one of saidplurality of transducers for restoring the display mechaNism to activecondition.
 13. Golf practice apparatus as defined in claim 12, andincluding also circuit means for disabling at least some of saidplurality of transducers in response to said second circuit means andfor restoring the disabled transducers to normal condition in responseto said first circuit means.
 14. Golf practice apparatus, comprising incombination structure defining a normal path of a golf club head duringa practice swing, a plurality of transducers for sensing a swinging clubhead and including transducers acting to produce first and second timingsignals in response to presence of the club head at respectivelongitudinally spaced points of the path, electronic circuit meanscontrolled by at least some of said transducers for producing a swingsignal that represents a characteristic of the swing, and timing circuitmeans responsive to the timing signals for producing a distance signalthat represents a ball flight distance signal that varies inversely withthe time interval between the timing signals, said timing circuit meansincluding means acting under control of the swing signal to modify thedistance signal in accordance with said flight characteristic.
 15. Golfpractice apparatus as defined in claim 14 and in which said timingcircuit means comprise clock means for producing a series of clockpulses, control means for modifying the frequency of the clock pulsesunder control of the swing signal, and counting means for counting clockpulses during the time interval between the timing signals.
 16. Golfpractice apparatus as defined in claim 14, and in which said timingcircuit means comprise a plurality of oscillating circuits for producingrespective series of clock pulses at different pulse frequencies, gatingcircuit means responsive to said swing signal for selecting one of saidpulse series, and counting means for counting the selected series ofclock pulses during the time interval between the timing signals. 17.Golf practice apparatus as defined in claim 16, and including also meansactuable to supply additional pulses at predetermined frequency to thecounting means in addition to said selected pulse series, and controlmeans for actuating the last-said means under control of the countingmeans.